Sprinkler systems for turf irrigation are well known. Typical systems include a plurality of valves and sprinkler heads in fluid communication with a water source, and a centralized controller connected to the water valves. At appropriate times the controller opens the normally closed valves to allow water to flow from the water source to the sprinkler heads. Water then issues from the sprinkler heads in predetermined fashion.
There are many different types of sprinkler heads, including above-the-ground heads and “pop-up” heads. Pop-up sprinklers, though generally more complicated and expensive than other types of sprinklers, are thought to be superior. There are several reasons for this. For example, a pop-up sprinkler's nozzle opening is typically covered when the sprinkler is not in use and is therefore less likely to be partially or completely plugged by debris or insects. Also, when not being used, a pop-up sprinkler is entirely below the surface and out of the way.
The typical pop-up sprinkler head includes a stationary body and a “riser” which extends vertically upward, or “pops up,” when water is allowed to flow to the sprinkler. The riser is in the nature of a hollow tube which supports a nozzle at its upper end. When the normally-closed valve associated with a sprinkler opens to allow water to flow to the sprinkler, two things happen: (i) water pressure pushes against the riser to move it from its retracted to its fully extended position, and (ii) water flows axially upward through the riser, and the nozzle receives the axial flow from the riser and turns it radially to create a radial stream. A spring or other type of resilient element is interposed between the body and the riser to continuously urge the riser toward its retracted, subsurface, position, so that when water pressure is removed the riser assembly will immediately return to its retracted position.
The riser assembly of a pop-up or above-the-ground sprinkler head can remain rotationally stationary or can include a portion that rotates in continuous or oscillatory fashion to water a circular or partly circular area, respectively. More specifically, the riser assembly of the typical rotary sprinkler includes a first portion (e.g. the riser), which does not rotate, and a second portion, (e.g., the nozzle assembly) which rotates relative to the first (non-rotating) portion.
The rotating portion of a rotary sprinkler riser typically carries a nozzle at its uppermost end. The nozzle throws at least one water stream outwardly to one side of the nozzle assembly. As the nozzle assembly rotates, the water stream travels or sweeps over the ground, creating a watering arc.
The trajectory of the watering stream is determined by the angle and shape of the nozzle within the nozzle assembly. In many prior art sprinklers, the trajectory of the watering stream is predetermined by the sprinkler manufacturer, often to achieve a maximum throw distance. However, these sprinklers prevent the user from modifying or otherwise adjusting the radius of these watering arcs (i.e. the length of the water stream), thereby limiting the ability to control and distribute water.
Other prior art sprinklers allow the user to change the trajectory of the watering stream by providing replacement nozzles that cause alternate, predetermined trajectories. However, the user must determine the exact size of the desired watering arc radius, then install a new nozzle rated for that distance. Thus the user is burdened with the added hassle of installing a new nozzle or nozzle base.
Newer prior art sprinklers, such as those seen in U.S. Pat. No. 6,869,026 (incorporated herein by reference), include a pivot mounted nozzle configured to follow a worm gear. A user rotates the worm gear from a screw mounted at the top of the sprinkler which causes the nozzle to change its trajectory. While these nozzle designs can achieve a variety of different nozzle angles, their additional components and complexity increase the cost to manufacture the sprinkler.
What is needed is a nozzle adjustment mechanism for a sprinkler that is simple to adjust, does not require added user expense to adjust, and does not significantly increase manufacturing costs.